PSU noise

I am actually posting here about PS and GPS compatibility. I was about to order a M4 when i read a thread that said it affects the FM and GPS signal. Even the M3 and M2 are known to do this. What are you guys using with good results? Just dont want to waist money.

This is my recommendation, http://store.mp3car.com/Mp3Car_DSATX_p/pwr-023.htm very solidly built and I have had no niose issues at all. Only problem with this unit when using the brainstem, is that the brainstem needs power from a different source to work effectively. easy to program and also has a plug-in support for a couple of FE's. SNO

I eventually found a way to solve the brainstem issue. I can now use the serial brainstem with a serial-usb adapter without any annoying bugs.
The braintem unstable issue (e.g. counldnt boot sometimes, no diagnostic data output) is due to the serial brainstem gets the 5v power from the dsatx J2 port, which somehow make the dsattx unstable.

The resolution is to connect only the TX and RX wires of the brainstem to the dsatx J2, meanwhile connects the 5v and ground wires to the harddisk power cable (I.e. the 4 pins power cable connecting the psu to the harddisk or cdrom), such that the brainstem will not get the power directly from the dsatx J2 port.

By doing this, the brainstem works when it can get the power from dsatx through the power cable, and I can us the brainstem for configuration and real time monitoring. Hibernate upon ignition works just perfect now.

It is only if you use the brainstem on the dsatx. The brainstem is an addon serial port to program different settings and to use plug-in's to have live data display from your power supply. If you just need standard power requirements the dsatx without brainstem works just fine. SNO

^ yep. i've got both the dsatx, and the brain stem, and have actually never needed the brainstem... it's main use is reprogramming specific functions(startup timers, etc), or as sno said, live data streams.

for me the stock settings or what's available with the adjustment pots is good enough for my install.

Just to add input to this, all of these DC-DC converters using a switching topology with lots of current being switched into the inductors. The frequency this current is being switched at has harmonics as well as the main frequency. It can effect any RF signal if improperly shielded. The M-Series are not exactly the kings of shielding, so that's why you get the noise.

While reading the post about the RF noise I did not see this fact 2k1Toaster. I would post it in there if you already didnt. Might help someone come up with a better way to shield it. I did see the box towards the end of the thread, but if it can be isolated to the switching on the board then maybe someone has a better idea of how to shield it.

The generation of Harmonic Interference in a SMPS has been posted in a number of threads here. Various fixes have been tried and posted, depending on the amplitude of the waveforms in the offending SMPS some of these have occasionally worked. I have posted a solution for removing almost all interference from the M4 and other SMPS, however it is expensive compared do the initial cost of the basic switch mode power supply (SMPS).

Most SMPS designs do not radiate directly from the PCB components but via the system interconnecting leads. Removing this noise from SMPS connection leads will not work with just a basic metal case as it requires filtering of every lead entry /exit point on the SMPS.

Again it depends on your system components, wiring, aerial location and the type of SMPS. Compounding this is the fact that SMPS interference changes with load and especially in the case of the M4, with input voltage. This is why some users have little problem but others suffer badly.

This is a "simplified" description of some of the possible interference modes in a system using any type of SMPS except those designed and sold specifically as low interference units for use in RF sensitive systems.

That is an extreme case and I hope not typical. SMPS supplies should have suppression as part of their design - in-line chokes and internal caps, appropriate PCB shielding, good PCB layout etc. I'm not sure if it is more a case of design abilities rather than the cost factor (IMO an essential cost unless extreme)?